The aim of this study is to compare the effect on ketone production of dietary an MCT supplement combined or not with physical exercise in two groups of women (N=10/group), healthy adults and patients with prediabetes. After an evaluation of the metabolism (a 4-hour visit with multiple blood samples) at the beginning of the study, all the participants are taken for one-week the MCT supplement alone follow by a one-week period of taking the MCT supplement in combination with physical exercise. At the end of each period of time, the 4-hour visit for the evaluation of the metabolism is repeated.